Eureka Seven fans cheered when Talho (ironically, a fellow Scrappy) gave Holland a good smack across the face when he was ready to abuse Renton again. They also cheered when Renton gave Holland a Badass Boast on how he came back to the Gekkostate for Eureka.
Laxus curbstompsall of Raven Tail, after they cheated at the games to make Fairy Tail lose (negating Lucy's Moment of Awesome by stopping her from using Urano Metoria against Flare and attacking Laxus all at once while using an illusion to make it look like he was suffering a Curb-Stomp Battle from his official opponent) and were being insufferably smug about it.
Even with the controversy involving how it happened, Erza beating Minerva still counts, especially with the latter begging for mercy by the end.
Natsu knocking out the former Council member Michello after he showed obnoxious cowardice and selfishness by abandoning his granddaughter to Jackal, trying to impose authority over the townspeople while demanding help, and insisting that he's far more important to save than a pregnant woman when Jackal puts Lucy in a Sadistic Choice over picking one not to blow up.
Silver curb-stomping Natsu, and freezing him solid comes off as this to those who were coming to really dislike the latter by the Tartaros arc.
In the Fate/Grand Order anime adaptation First Order, ShinjiMatou has a cameo as one of Medusa's many stone victims. Then she shatters him.
Takeuchi-sensei, Shouko and Shouya's elementary school teacher and the shining example of Adults Are Useless, shows up when Shouya and Mashiba visit the school and he's just as shallow as ever. Fans were very satisfied to watch Mashiba - who had just been present to request that he and his friends be permitted to shoot their film at Takeuchi's school - splash the contents of his water bottle in the remorseless jackass's face.
Early on in the story, Shouya gets an overdose of his own medicine after Nishimiya is forced to leave. This ends up leading to his becoming The Atoner, which, in turn, leads to his being Rescued from the Scrappy Heap... for most people. For those who can't bring themselves to view him sympathetically after all he had done when he was in elementary school, the entire series is pretty much this to him.
In Kotoura-san, Hiyori was at first seen as The Scrappy after MindRaping and then bullying Haruka and also sending four adults to attack her Childhood Friend Manabe, all because Manabe dated Haruka, not her. After her HeelFace Turn, Hiyori changes from antagonistic bully to group Butt-Monkey. The poster Haruka gets from Manabe in episode 5 (which Haruka used for laughing material) says it all. Likewise, Manabe, for a short time at least, treats Hiyori with hilarious contempt once her friendship with Haruka is solidified.
Jail: I've been keeping myself healthy. This transparent prison is unexpectedly comfortable. Cinque: Uno and Tre are healthy as well. Jail: They haven't changed at all. Quattro has even gotten a bit fat.
MegaMan NT Warrior had the episode titled "The Purloined Princess" which brought back Yai in the show, only for the main cast to show that they are just as sick of her as the fandom.
A comment on the first video: It's like the writers knew some people wouldn't like Piplup.
Another example comes with Cameron. After defeating both Bianca and Ash, he gets defeat 3-6 by Virgil. It even went so far that Cameron was omitted from the dub's usage of footage from the "Be An Arrow" opening and a set of Event Pokémon based on his roster where not released in the US. It seems The Pokémon Company is aware of the backlash Cameron has received. In a downloadable tournament, in fact, you get to fight Cameron and Virgil, allowing haters to get their revenge on them.
Valvrave the Liberator has Q-Vier, the only actually evil member of the Dorssian elite team, who was otherwise composed of Anti Villains. Lacking any kind of Hidden Depths, as well as A-Drei's high-minded ideals, X-Eins' strategic prowess and even H-Neun's friendliness, Q-Vier only cared about killing people and was responsible, either directly or indirectly, for the deaths of several more sympathetic (or even just more popular) characters (the names Figaro, Aina, Lieselotte and Yamada come to mind). Therefore, when he was killed (though unintentionally) by A-Drei during the last episode, it is safe to say that nobody felt sad for him (The writers wanted it to be an Alas, Poor Villain moment, but Q-Vier was just too widely hated for it to work).
Episode 8 of Gundam Build Fighters opens with a Cameo from the reviled G-Saviour, only for it to be quickly and unceremoniously sliced in half by Nils Nielsen's Hyaku Shiki.
In Mobile Suit Gundam ZZ, we see a return appearance of Wong Lee, one of the AEUG's higher-ups. Wong was widely disliked by fans due to beating the crap out of Kamille in his first scene (Kamille arguably had it coming, but Wong really went over-the-top), and then generally being whiny and useless for the rest of the series. When he tries to administer a similar "correction" to Judau, however, Judau knees him in the gut and takes off, much to the amusement of the fanbase.
Kantai Collection's Animated Adaptation gets one in episode 9: Ooi's Clingy Jealous Girl behavior reaches a head when she whines about a photo of her and Kitakami getting destroyed while ignoring the fact that the entire Naval District — the fleet girls' home — was bombed into splinters by the Abyssal Fleet. Kitakami herself says "Ooi, this isn't the time for that" while calmly trying to clean things up.
Kyubey suffers from a realization that he shouldn't have toyed with human emotions and a BSOD in Madoka Rebellion.
In Danganronpa: Trigger Happy Havoc, Hagakure got a lot of hatred for being a Flat Character who didn't contribute much to the story. In Danganronpa 3, Monokuma tells the audience during a recap that he is stuck outside the building where all of the action is taking place, and therefore being excluded from the main plot, "Because nobody likes him."
Any time Mineta from My Hero Academia gets hurt in any way is usually met with cheering from fans, especially if it's from a girl he was just trying to grope.
The last episode of the Daily Life with Monster Girl anime has the unnamed couple of racist assholes apparently killed in a car crash caused by Centorea. It's probably karmic punishment because the man of the couple tried to rape Centorea, together with other thugs, in an earlier episode.